1. Field of the Invention
This invention relates to an injection molding machine comprising means for separating usable moldings from unusable parts. More particularly, the invention relates to such a machine which comprises an injection molding unit and a clamping unit, each of which units is mounted in a horizontal orientation on a pedestal which rests on an approximately rectangular undersurface. The machine further comprises an ejector for consecutively ejecting usable moldings and unusable parts, such as rejects and/or sprues, from the opened injection mold. The machine further comprises sorting means, which are accommodated in the pedestal under the injection mold and comprise a sorting plate, which is pivoted on a horizontal axis and is provided on opposite sides with sliding surfaces for spatially separating the unusable parts (rejects and sprues) from the usable moldings. The sorting means further comprise a motor-driven turning drive for pivotally moving the sorting plate in the interval of time between the ejection of the usable moldings and of the unusable parts in respective inclined positions, in which the sorting plate causes the usable moldings and the unusable parts to be separated in that they are respectively caused to slide down in mutually opposite directions on respective sliding surfaces of the sorting plate.
2. Description of the Prior Art
U.S. Pat. No. 3,776,675 discloses an injection molding machine which is of that kind and in which the pivotal axis 35 of the sorting plate extends in the plane of symmetry (b--b in FIG. 3) of the injection molding machine. As a result, the usable moldings and the unusable parts are conveyed out of the pedestal transversely to the plane of symmetry of the injection molding machine across respective longitudinal side walls of the pedestal. Additional space is required on the longitudinal sides of the pedestal for means for carrying off or for a further processing of the usable moldings and of the unusable parts. In case of trouble involving the sorting means, which are integrated in the pedestal, the operation cannot be resumed until the repair has been completed because the sorting means cannot be replaced by an operative replacement sorting means.
From U.S. Pat. No. 4,608,008 it is known to provide a belt conveyor in a unit which is removable from the pedestal of the machine and so to arrange such unit that the usable moldings can be moved out of the pedestal at one end in a direction which is parallel to the plane of symmetry of the injection molding machine. But the unusable parts cannot be separated because the vertical projection of the mold is within the conveying surface of the conveyor belt.
U.S. Pat. No. 4,321,027 discloses a relatively large injection molding machine, in which a three-part mold is employed and the rejects and sprues will anyway fall out of the three-part mold in an area which is spaced from the area in which the usable moldings drop out of the mold (loc. cit., lines 18 to 29 of column 1 and lines 32 to 38 of column 2). Because the parts are dropped at spaced apart locations there is no need for space-occupying additional means for separating the sprues. Such means are known from U.S. Pat. No. 3,776,675 mentioned above. But the provision of such means will be essential if a replaceable size reduction unit is to be used also in small or very small injection molding machines of various types and where simple injection molds are employed. This has not been possible thus far owing to a lack of space.